The present invention relates to apparatus for counteracting torsional stresses, and more particularly to improvements in apparatus for damping torsional vibrations between two or more coaxial flywheels. Still more particularly, the invention relates to improvements in torsional vibration damping apparatus which can be installed between the output shafts of the engines and the input shafts of the change-speed transmissions in motor vehicles.
German Offenlegungsschrift No. 34 40 927 discloses a torsional vibration damping apparatus which is installed between the crankshaft of an internal combustion engine and the input shaft of the change-speed transmission in an automotive vehicle. The apparatus comprises two coaxial flywheels one of which is non-rotatably secured to the crankshaft and the other of which can be coupled to the input shaft of the change-speed transmission by a friction clutch. The damper which is installed between the two flywheels comprises at least one set of energy storing springs (normally coil springs) and, if necessary, friction generating means to oppose each stage or selected stages of angular movement of the flywheels relative to each other. Each flywheel rotates with one or more disc-shaped components which have windows for the coil springs so that the coil springs are caused to store or dissipate energy in response to angular movement of one flywheel relative to the other flywheel and/or vice versa. The friction generating means engage the disc-shaped components and oppose axial movements of the flywheels relative to one another. The energy storing or friction-generating elements between the two flywheels are compelled to rub against each other and/or against the disc-shaped components of the flywheels in response to movement of one flywheel relative to the other flywheel.